In order to adhere room temperature vulcanizable silicone elastomers to various substrates it has usually been necessary to first coat or treat the substrate with a primer. The typical primers employed for this purpose have heretofore contained an organic solvent and a coupling agent. U.S. Pat. Nos. 4,749,741; 4,681,636, and 3,671,483 disclose such primer compositions.
Because of increasing concerns about the release of volatile organic solvents to the atmosphere in various organic products such as paints, sealants, aerosols, and the like and the deleterious effects on the environment of the release of volatile organic compounds into the environment or atmosphere, it has become desirable to minimize the volatile organic content of many commercially useful products. The absence of solvents, which dilute the effective concentration of high molecular weight materials that are also usually viscous renders the simple removal of solvent from formulations a challenging task. This is because the compositions themselves must be re-formulated and frequently there must be a change in the molecular architecture of the compounds employed in order to secure the same benefits of a given intended product while reducing the amount of volatile organic matter present in the formulation.
In the case of sealants and room temperature vulcanizable silicone compositions some progress towards this goal has been made by recent developments in the art. U.S. Pat. No. 5,238,708 discloses a primer suitable for use with room temperature vulcanizable compositions comprising an organotitanate and a tin carboxylate. U.S. Pat. No. 4,332,844 discloses a composition comprising an alkoxy containing silicone compound, an organohydrogensilicon compound, and an organotitanate that improves the adhesion between a silicone rubber and a substrate.